Russia Sent Tanks to Separatists in Ukraine, U.S. Says

WASHINGTON — The State Department confirmed on Friday that Russia had sent tanks and other heavy weapons to separatists in Ukraine.

A column of three T-64 tanks, several BM-21 “Grad” multiple rocket launchers, and other military vehicles crossed the border near the Ukrainian town of Snizhne, State Department officials said. Reports and images of the weapons circulated on Thursday, but there were conflicting claims about where they had come from.

“This is unacceptable,” said Marie Harf, a State Department spokeswoman. “A failure by Russia to de-escalate this situation will lead to additional costs.”

A Western official said that intelligence about the movement of the tanks and other weapons into Ukraine had been shared on Friday with NATO allies. Secretary of State John Kerry complained earlier this week about the flow of Russian arms to separatists in Ukraine in a phone call to Sergey V. Lavrov, the Russian foreign minister.

The T-64 is an obsolescent tank no longer in active use by Russian forces, but it is still kept in storage in southwest Russia.

“Russia will claim these tanks were taken from Ukrainian forces, but no Ukrainian tank units have been operating in that area,” the State Department said Friday afternoon. “We are confident that these tanks came from Russia.”

“We also have information that Russia has accumulated multiple rocket launchers at this same deployment site in southwest Russia, and these rocket launchers also recently departed,” it added. “Internet video has shown what we believe to be these same rocket launchers traveling through Luhansk.”

At a summit meeting of the Group of 7 major industrial democracies in Brussels on June 5, President Obama demanded that President Vladimir V. Putin of Russia stop the flow of fighters and arms across the Russia-Ukraine border and press the pro-Russia separatists in eastern Ukraine to disarm, relinquish seized public buildings and join talks with the central authorities in Kiev, the Ukrainian capital.

Mr. Obama said Russia would have to comply within “the next two, three, four weeks,” and added, “If Russia’s provocations continue, it’s clear from our discussions here that the G-7 nations are ready to impose additional costs on Russia.”